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Old 06-25-2012, 09:22 AM   #1
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A/C thermostat question

I have a 2011 Rockwood 8280ws fifth wheel. The problem is with the A/C only, heater side works fine. We like to set the thermostat at night to keep the temp. at 70 to 72 deg. If I set it on 72 deg. the A/C will continue to run and the temp. will get to 66 deg. before turning off. If I move the setting up a deg. or 2 the unit will shut off, but will not come on again on it's own till the inside temp. reaches 75 to 76 deg. The unit is a Coleman Mach. 13,500btu with matching thermostat. Has anyone had this problem and how can it be corrected? During the daytime we set it on 77 deg. and everything works fine. Thanks, Tom-s

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Old 06-25-2012, 02:14 PM   #2
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It's because of the cheap thermostats that come with the units. The slide type have a -+5 range for temp. A digital thermostat has a range -+.5 to 1. I would suggest a thermostat upgrade. I did this in my last trailer and it worked great. The only trick is wiring a little switch for the hi / low fan speeds.

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Old 06-25-2012, 02:30 PM   #3
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Old 06-25-2012, 04:24 PM   #4
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There are lots of good threads on how to upgrade to a digital Hunter T-stat (about $20 at WalMart or Home Depot). Relatively easy to do, especially if you don't bother with the high/low switch for the fan (your AC at home doesn't have high or low fan settings, it just runs on high, so many use a home-style thermostat, just set for high speed).
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Old 06-25-2012, 04:35 PM   #5
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Hunter digital thermostat is the fix!

A digital thermostat is the only way to go. As mentioned on a post already, the Hunter thermostat is only about $20.00, easy to install. Listed are many detailed mods on the net for the wiring and 2 speed switch install.

My last three RV's was one of the first changes I made, installed a Hunter digital thermostat.

This web site will give you the detailed mod for the Hunter fix.

RV Mods, RV Modifications, RV Upgrades, RV Tips, RV eBooks |

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Old 06-26-2012, 08:55 AM   #6
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I really appreciate the good advice. Going to town today to get one. The temp. today is forecast to be 105 deg. so I may not mess with it until a cooler day. Again thanks to all who helped and thanks to Forest River for this web-site . Respectfully, Tom-s
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Old 06-27-2012, 02:37 PM   #7
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There is a quirk with using "residential" digital thermostats (and some Dometic digitals). They don't know what to do when they read temps over 100F and temps below 50(?) as their set points don't go that high/low. The thermostat will read "Error" or "E2" depending on the manufacture. The workaround is to put something cool (or warm) to fake the thermosat into a reading it knows how to handle OR manually jump (connect) the appropriate themostat wires. Depending on the AC and Thermostat makers it varies so when you follow the mod instructions for your specific set up you will know.

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